Data.php

<?php 
// Data Helper:
class Kirchbergerknorr_RelevanceIndexer_Helper_Data extends Mage_Core_Helper_Abstract
{
    public function log($message, $level = null, $file = 'kk_relevanceindexer.log', $forceLog = false)
    {
        Mage::log($message, $level, $file, $forceLog);
    }
}

// Usage
Mage::helper('kk_relevanceindexer')->log($message);